Refactoring

Display changes in the Refactoring preview dialog

Support Undo

Any XML changes will be done without the user having to check the box 'Update fully qualified names in non-Java text files'. Currently the user can get java type renames to be completed in the persistence.xml by checking that box, but a java type delete will not edit the persistence.xml.

Support refactorings in 1 project affecting any JpaProject in the workspace